doc (book)[12/14]: "Cargo Guide"/"Continuous Integration": link terms to glossary

The following term(s) are linked to their Glossary entries:
    - package

Author: salewski

src/doc/src/guide/continuous-integration.md

@@ -2,7 +2,8 @@
 
 ### Travis CI
 
-To test your package on Travis CI, here is a sample `.travis.yml` file:
+To test your [package][def-package] on Travis CI, here is a sample
+`.travis.yml` file:
 
 ```yaml
 language: rust
@@ -86,3 +87,5 @@ This will test and build documentation on the stable channel and nightly
 channel, but any breakage in nightly will not fail your overall build. Please
 see the [builds.sr.ht documentation](https://man.sr.ht/builds.sr.ht/) for more
 information.
+
+[def-package]:  ../appendix/glossary.md#package  '"package" (glossary entry)'